JP7023391B2 - Pattern forming method and manufacturing method of uneven structure - Google Patents

Description

The present invention relates to a pattern forming method and a method of manufacturing an uneven structure using the pattern.

In recent years, in the manufacturing process of semiconductor devices (for example, semiconductor memory, etc.), a mold member (mold) having a fine concavo-convex structure formed on the surface of the substrate is used, and the fine concavo-convex structure is transferred to a workpiece such as a substrate. Nanoimprint technology, which is a pattern forming technology for transferring a fine concavo-convex structure at the same magnification, is used.

A nanoimprint mold having such a fine concavo-convex structure generally forms a resist pattern corresponding to the fine concavo-convex structure through an electron beam drawing process, an ultraviolet exposure process, and a development process on a resist film provided on the surface of a substrate. , The substrate on which the resist pattern is formed is subjected to an etching process using the resist pattern as a mask, and is manufactured by a so-called electron beam lithography method or photolithography method.

It takes a lot of time and cost to manufacture this nanoimprint mold. Therefore, in the manufacturing process of semiconductor devices and the like, generally, the nanoimprint mold manufactured by the electron beam lithography method or the photolithography method as described above is used as a master mold, and the nanoimprint mold is manufactured by the imprint lithography method using the master mold. Nanoimprint mold (replica mold) is used.

In a semiconductor device such as a semiconductor memory, a fine uneven structure of a nanoimprint mold (generally a replica mold) is transferred to a resist film provided on the surface of a substrate by an imprint method to form a fine resist pattern, and the resist pattern is formed. Is formed, the substrate is subjected to an etching process using the resist pattern as a mask to form a fine concavo-convex structure on the substrate, and then the substrate is manufactured through a predetermined step.

As described above, a nanoimprint mold having a fine concavo-convex structure, a semiconductor device, or the like is manufactured by forming a resist pattern having fine dimensions corresponding to the fine concavo-convex structure on a substrate by an imprint method.

The resist pattern thus formed is used as a mask for etching a substrate, a hard mask layer provided on the substrate, and the like. Therefore, in order to form a fine concavo-convex structure in nanoimprint molds, semiconductor devices, etc. with high accuracy, the resist pattern is required to have etching resistance to the extent that it does not disappear during the etching process of the substrate or the hard mask layer. Will be done.

Conventionally, a method of transferring a resist pattern to a substrate with high accuracy by depositing a side wall protective material on at least the side wall of the resist pattern by ALD (atomic layer deposition) or the like has been proposed (see Patent Document 1).

Further, in a self-assembling film using a block copolymer composed of polymethyl methacrylate (PMMA) and polystyrene (PS), PMMA and trimethylaluminum (TMA) are chemically reacted inside the phase-separated PMMA pattern. Therefore, a method for improving the etching resistance of the PMMA pattern is known (see Non-Patent Document 1).

JP-A-2015-122497

ACS NANO, Quing Peng et al., Vol. 5, No. 6, pp. 4600-4606, 2011

In Patent Document 1, by depositing a side wall material on the side wall of a resist pattern of about 10 nm with a film thickness of about 1 to 2 nm, the uneven pattern composed of the resist pattern and the side wall material exhibits the desired etching resistance. It is disclosed that the uneven pattern can be transferred to a substrate with high accuracy.

In the method described in Patent Document 1, the substrate is etched after removing the side wall material deposited in the recesses between the resist patterns, but in the process of removing the side wall material deposited in the recesses between the resist patterns. Since the side wall material deposited on the top of the resist pattern is also removed, the top of the resist pattern is exposed. If the substrate is etched in that state, the resist pattern may disappear during the etching process of the substrate.

In order to prevent the resist pattern from disappearing during the etching process of the substrate or the hard mask layer, it is necessary to form a resist pattern having a height corresponding to the etching selection ratio with the substrate or the hard mask layer. However, while the size of the resist pattern becomes fine (half pitch of about 5 to 30 nm), when trying to secure the desired height of the resist pattern, the aspect ratio (ratio of height to size) inevitably increases. .. For example, the size and aspect ratio of the resist pattern formed by the imprint lithography method are determined by the shape of the master mold, the imprint material and the transfer method, but they are fine and have a high aspect ratio (aspect ratio of 2.5 or more). ) Is technically extremely difficult to form the resist pattern with high accuracy. Even if it is possible to form a resist pattern having fine dimensions and a high aspect ratio, there is a problem that the resist pattern having a high aspect ratio is easily broken and cannot function as an etching mask.

If the resist pattern has fine dimensions and a low aspect ratio (aspect ratio less than 2), it can be formed with high accuracy by setting the shape of the master mold, the imprint material, and the transfer conditions. However, when the substrate or the hard mask layer is etched using such a resist pattern as a mask, there is a problem that the resist pattern disappears during the etching process of the substrate or the hard mask layer.

Further, in the method described in Non-Patent Document 1, the PMMA pattern is formed by chemically reacting with trimethylaluminum (TMA) inside the PMMA pattern in a self-assembled membrane using a block copolymer composed of PMMA and PS. However, there is a problem that it is technically extremely difficult to finely control the dimensions and the like of the PMMA pattern formed in the self-assembled film with high accuracy.

In view of such a problem, the present invention is a method of forming an uneven pattern having etching resistance to such an extent that it can sufficiently function as an etching mask even with fine dimensions by an imprint method, and a method thereof. It is an object of the present invention to provide a method for manufacturing a concavo-convex structure using a method.

In order to solve the above problems, the present invention prepares a base material having a first surface and a second surface facing the first surface, and an imprint mold having a pattern forming surface formed by forming a plurality of concave patterns. An active energy ray-curable resin is interposed between the first surface of the base material and the pattern forming surface of the imprint mold to perform an imprint process, and a plurality of convex portions corresponding to the plurality of concave patterns. A pattern forming step of forming a resin pattern having a concave portion and a residual film portion located at the bottom of the concave portion on the first surface of the base material, and removing the residual film portion of the resin pattern. By exposing the resin pattern from which the residual film portion has been removed to the step and the first gas containing the inorganic compound exhibiting Lewis acidity under predetermined conditions, the inorganic compound and the active energy ray constituting the resin pattern are exposed. A first gas exposure step of chemically reacting the curable resin inside the resin pattern, and a second gas exposure step of exposing the resin pattern to a second gas containing an oxidizing agent after the first gas exposure step. Provided is a pattern forming method, characterized in that each of the first gas exposure step and the second gas exposure step is performed for 1 second or longer .
Further, in the present invention, a base material having a first surface and a second surface facing the first surface and an imprint mold having a pattern forming surface formed by forming a plurality of concave patterns are prepared, and the first of the base materials is prepared. An active energy ray-curable resin is interposed between the surface and the pattern forming surface of the imprint mold to perform imprint processing, and the plurality of convex portions, the plurality of concave portions, and the concave portions corresponding to the plurality of concave patterns are formed. A pattern forming step of forming a resin pattern having a residual film portion located at the bottom on the first surface of the base material, a residual film portion removing step of removing the residual film portion of the resin pattern, and Lewis acidity are performed. By exposing the resin pattern from which the residual film portion has been removed to the first gas containing the indicated inorganic compound under predetermined conditions, the inorganic compound and the active energy ray-curable resin constituting the resin pattern are described. It has a first gas exposure step of chemically reacting inside the resin pattern, and a second gas exposure step of exposing the resin pattern to a second gas containing an oxidizing agent after the first gas exposure step. In the gas exposure step, the resin material constituting the resin pattern is heated under a temperature condition lower than the glass transition temperature, and the resin pattern from which the residual film portion is removed is exposed to the first gas to expose the second gas. Provided is a pattern forming method characterized in that the resin pattern is exposed to the second gas by heating under a temperature condition lower than the glass transition temperature of the resin material constituting the resin pattern in the step.

As a result of diligent studies by the present inventors, when the resin pattern formed on the first surface of the base material by the imprint treatment is exposed to the first gas and the second gas, the resin pattern (convex portion) is deformed. It became clear that it would end up. It is considered that this is because the resin pattern is integrally formed by the residual film portion of the thin film, and is caused by the distortion that may occur in the resin pattern when exposed to the first gas and the second gas. However, according to the above invention, since the residual film portion is removed from the resin pattern formed by the imprint treatment and the plurality of convex portions are independently exposed to the first gas and the second gas in order, the pattern is formed. Deformation can be prevented, and a pattern with improved etching resistance can be formed with high accuracy.

In the above invention, it is preferable to repeat the gas exposure step including the first gas exposure step and the second gas exposure step a plurality of times, and the time for exposing the resin pattern to the first gas in the first gas exposure step is preferable. The time for exposing the resin pattern to the second gas may be longer than the time for exposing the resin pattern to the second gas in the second gas exposure step, and the time for exposing the resin pattern to the first gas in the first gas exposure step may be longer than the time for exposing the resin pattern to the second gas. The gas exposure step may be repeated 5 times or more, which is shorter than the time required to expose the resin pattern to the second gas. The thickness of the residual film portion is preferably 1 to 20 nm, the size of the resin pattern is preferably 5 nm or more and less than 30 nm at a half pitch, and the aspect ratio of the resin pattern is 0.5 to 2. It is preferably .5, and a quartz glass substrate or a silicon substrate can be used as the substrate .

Further, in the present invention, a pattern is formed on the first surface of the base material by the pattern forming method according to the present invention, and the first surface side of the base material is etched using the pattern as a mask. Provided is a method for manufacturing a characteristic concavo-convex structure.

Further, in the present invention, a pattern is formed on the hard mask layer in the base material on which the hard mask layer is formed on the first surface by the pattern forming method according to the present invention, and the pattern is used as a mask. Provided is a method for manufacturing an uneven structure, which comprises forming a hard mask pattern by etching a hard mask layer and etching the first surface side of the base material using the hard mask pattern as a mask. ).

According to the present invention, a method of forming a concavo-convex pattern having etching resistance sufficient to function as an etching mask even with fine dimensions by an imprint method with high accuracy, and a concavo-convex structure using the method. Can be provided with a method of manufacturing.

FIG. 1 is a flowchart showing each step of the pattern forming method according to the embodiment of the present invention. FIG. 2 is a process flow chart showing each step of the imprint step and the residual film portion removing step in the pattern forming method according to the embodiment of the present invention in a cut end view. FIG. 3 is a process flow chart showing each step of the gas exposure step in the pattern forming method according to the embodiment of the present invention and the etching step in the manufacturing method of the uneven structure in a cut end view. FIG. 4 is a configuration diagram schematically showing an apparatus capable of carrying out the gas exposure step according to the embodiment of the present invention. FIG. 5 is a graph showing the resist film thickness results in Examples (Examples 1 to 5) and Comparative Examples (Comparative Examples 1 to 3). FIG. 6 is a chart showing the result of time-of-flight secondary ion mass spectrometry in Test Example 1. FIG. 7 is an electron microscope image showing the uneven pattern formed in Example 6. FIG. 8 is an electron microscope image showing the uneven pattern formed in Comparative Example 4. FIG. 9 is an electron microscope image showing an uneven pattern before heating in the heat resistance test of Test Example 2. FIG. 10 is an electron microscope image showing an uneven pattern after heating in the heat resistance test of Test Example 2.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing each step of the pattern forming method according to the present embodiment, and FIG. 2 is a cut end view of each step of the imprint step and the residual film portion removing step in the pattern forming method according to the present embodiment. FIG. 3 is a process flow chart showing each step of the gas exposure step in the pattern forming method according to the present embodiment and the etching step in the manufacturing method of the uneven structure in the cut end view. Yes, FIG. 4 is a configuration diagram schematically showing an apparatus capable of carrying out the gas exposure step in the present embodiment.

<Imprint process>
A base material 10 having a first surface 11 and a second surface 12 facing the first surface 11 is prepared, and a resin uneven pattern 31 is formed on the first surface 11 of the base material 10 (S01 in FIG. 1 and FIG. 2 (A). )-(C)).

The base material 10 includes, for example, quartz glass, soda glass, fluorite, calcium fluoride substrate, magnesium fluoride substrate, glass substrate such as acrylic glass, polycarbonate substrate, polypropylene substrate, resin substrate such as polyethylene substrate, and among these. A transparent substrate such as a laminated substrate formed by laminating two or more substrates arbitrarily selected from the above; a metal substrate such as a nickel substrate, a titanium substrate, or an aluminum substrate; a semiconductor substrate such as a silicon substrate or a gallium nitride substrate may be used. can.

In the present embodiment, a hard mask layer 20 made of metallic chromium, chromium oxide, chromium nitride, chromium oxynitride, or the like is provided on the first surface 11 of the base material 10. According to the pattern forming method according to the present embodiment, the uneven pattern 33 with improved etching resistance (see FIG. 3B) can be formed, so that the thickness of the hard mask layer 20, that is, the hard mask layer 20 can be formed. Even if the etching amount of the hard mask layer 20 is increased, the uneven pattern 33 does not disappear during the etching process of the hard mask layer 20. Therefore, in the present embodiment, the thickness of the hard mask layer 20 can be set to about 1 to 30 nm, whereby the uneven structure 1a formed on the first surface 11 side of the base material 10 (FIG. 3 (E). )) The aspect ratio can be increased. It should be noted that the present embodiment is not limited to such an embodiment, and the hard mask layer 20 may not be provided.

The thickness of the base material 10 can be appropriately set in the range of, for example, about 300 μm to 10 mm in consideration of the strength of the substrate, handling suitability, and the like. In the present embodiment, "transparent" means that the transmittance of light rays having a wavelength of 300 to 450 nm is 85% or more, and is preferably 90% or more.

The resin material constituting the resin uneven pattern 31 reacts with the inorganic compound contained in the first gas exposed to the uneven pattern 32 in the gas exposure step (first gas exposure step, S03 in FIG. 1) described later. As long as it has a reactive functional group exhibiting sex, it is not particularly limited. As the resin material, an active energy ray-curable resin such as an acrylic resin, a methacrylic resin, and an epoxy resin generally used for imprint processing using an imprint mold (for example, an ultraviolet curable resin and an electron beam curable resin). Etc.) can be exemplified. Examples of the reactive functional group showing reactivity with the inorganic compound contained in the first gas include a carbonyl group, a thiocarbonyl group, an acryloyl group, a hydroxyl group, a sulfanyl group, an epoxy group and the like.

The resin concavo-convex pattern 31 is the first surface of the base material 10 after being imprinted using an imprint mold 40 (master mold) having a pattern forming surface on which the concavo-convex pattern 41 corresponding to the resin concavo-convex pattern 31 is formed. Formed on 11. Specifically, first, an imprint mold 40 having an unevenness pattern 41 corresponding to the unevenness pattern 31 made of resin is prepared, and an active energy ray-curable resin is applied on the hard mask layer 20 of the base material 10 to inject. The printed resin film 30 is formed (see FIG. 2A).

Next, the uneven pattern 41 of the imprint mold 40 is pressed against the imprint resin film 30 to fill the uneven pattern 41 with the active energy ray-curable resin, and the imprint resin film 30 is cured in that state (FIG. 2). (B)). As a method for curing the imprint resin film 30, a method corresponding to the curing type of the resin material constituting the imprint resin film 30 may be adopted. For example, if the resin material is an ultraviolet curable resin, the in-print resin film 30 may be cured. A method of irradiating the imprint resin film 30 with ultraviolet rays via the print mold 40 can be adopted.

The imprint mold 40 is pulled away from the cured imprint resin film 30 (see FIG. 2C). In this way, the resin uneven pattern 31 having the plurality of convex portions 31a and concave portions 31b and the residual film portion 31c located at the bottom of the concave portions 31b can be formed by the imprint method.

The shape of the resin uneven pattern 31 is not particularly limited, and examples thereof include a line-and-space shape, a hole shape, a pillar shape, and the like depending on the application. The size of the resin uneven pattern 31 may be any size according to the intended use, but if it is 5 nm or more and less than 30 nm (0X to 2X nm), particularly 10 nm or more and less than 20 nm (1X nm), the pattern forming method according to the present embodiment. This is preferable because the effect of The aspect ratio of the resin uneven pattern 31 is not particularly limited, but is preferably, for example, about 0.5 to 10, and more preferably about 0.5 to 2.5. In the present embodiment, since the etching resistance of the uneven pattern 33 that can be used as an etching mask is improved, even if the aspect ratio is relatively small (for example, about 0.5 to 2.0), during the etching process. The function as an etching mask can be sufficiently fulfilled without the uneven pattern 33 disappearing.

<Remaining film removal process>
The bottom of the concave portion 31b of the resin uneven pattern 31 formed by the imprinting step (S01 in FIG. 1, FIG. 2 (A), (B)) has a predetermined thickness (about 1 to 20 nm, preferably 5). There is a residual film portion 31c (about 10 nm) (see FIG. 2C). When the resin uneven pattern 31 having the residual film portion 31c is subjected to a gas exposure step (see S03 to S06 in FIG. 16, FIGS. 3A and 3B) described later, the resin unevenness pattern 31 is deformed. It ends up. Therefore, in the present embodiment, the residual film portion 31c is removed before the gas exposure step (see S03 to S06 in FIG. 16, FIGS. 3A and 3B) is carried out (FIG. 2D). )reference). As a result, the uneven pattern 32 from which the residual film portion 31c is removed is formed on the base material 10.

Examples of the method for removing the residual film portion 31c include ashing treatment with oxygen plasma, UV ozone treatment with ultraviolet light, VUV treatment with vacuum ultraviolet light, and the like.

<Gas exposure process>
Next, the base material 10 having the uneven pattern 32 is exposed to a predetermined gas (S03 to S06 in FIG. 1). Specifically, first, the unevenness pattern 32 is exposed to a first gas containing an inorganic compound showing Lewis acidity and containing an inert gas such as nitrogen (N ₂ ) as a carrier gas under predetermined conditions (first gas). Exposure step, S03 in FIG. 1). By exposing the concavo-convex pattern 32 to the first gas, the reactive functional groups in the chemical structure of the resin material constituting the concavo-convex pattern 32 can be chemically reacted with the inorganic compound inside the concavo-convex pattern 32. The "predetermined conditions" in the first gas exposure step (S03 in FIG. 1) include the dimensions of the uneven pattern 32, the type of resin material constituting the uneven pattern 32, and the type of the inorganic compound contained in the first gas. Conditions can be set as appropriate in consideration of various conditions such as the hard mask layer 20 for etching using the uneven pattern 33 with improved etching resistance as a mask and the type of material constituting the base material 10.

Examples of the inorganic compound contained in the first gas include trimethylaluminum (Al (CH ₃ ) ₃ , TMA), methyltrichlorosilane, tris (dimethylamino) aluminum, tetrakis (diethylamino) titanium (IV), and titanium (IV) iso. Examples thereof include propoxide, tetrachlorotitanium (IV), silicon tetrachloride, tris (tert-pentoxy) silanol, and bis (ethylmethylamino) silane. When the inorganic compound contained in the first gas is trimethylaluminum (TMA) and the reactive functional group is a carbonyl group, the trimethylaluminum (TMA) and the carbonyl group are as shown in the following reaction formula (1). react.

The gas exposure step (S03 to S06 in FIG. 1) has, for example, a chamber 51, a gas inlet 52, and a gas exhaust port 53, and is a base on which an object to be treated (in this embodiment, an uneven pattern 32 is formed). This can be performed using a sequential gas phase chemical reaction apparatus 50 (see FIG. 4) including a stage 54 on which the material 10) can be placed and a heater capable of heating the object to be processed placed on the stage 54. .. The gas exposure step (S03 to 06 in FIG. 1) may be performed using an ALD (atomic layer deposition) device.

The time for exposing the uneven pattern 32 to the first gas (first gas exposure time) is 1 second or longer, preferably 30 to 10000 seconds. When the exposure time of the first gas is less than 1 second, the inorganic compound contained in the first gas is bonded to the reactive functional group located on the outermost surface of the uneven pattern 32 and chemically adsorbed on the outermost surface of the uneven pattern 32. The action of the oxidizing agent contained in the second gas, which will be described later, causes a thin film of an inorganic oxide (so-called ALD film) to be formed on the surface of the uneven pattern 32. When a thin film of oxide is formed on the surface of the uneven pattern 32, it becomes difficult for the inorganic compound to react inside the uneven pattern 32. Therefore, a gas exposure step (FIG. 1) including a second gas exposure step (S05 in FIG. 1) described later is included. While repeating steps 1 (S03 to S06) a plurality of times, a thin film of an inorganic oxide is formed in multiple layers, and the dimensions of the uneven pattern 32 fluctuate. On the other hand, if the first gas exposure time is 1 second or more, the inorganic compound also reacts and bonds with the reactive functional group inside the uneven pattern 32, so that the dimensions of the uneven pattern 32 are not substantially changed. Etching resistance can be improved.

In the first gas exposure step (S03 in FIG. 1), the concave-convex pattern 32 is exposed to the first gas while being heated under a temperature condition equal to or lower than the melting point of the resin material constituting the concave-convex pattern 32, preferably lower than the glass transition temperature. Is preferable. By exposing the concavo-convex pattern 32 to the first gas while heating it, the reaction between the reactive functional group and the inorganic compound contained in the first gas can be promoted inside the concavo-convex pattern 32. Since the first gas exposure time is relatively long, if the unevenness pattern 32 is exposed to the first gas under temperature conditions equal to or higher than the glass transition temperature of the resin material constituting the unevenness pattern 32, the unevenness made of resin is used. The pattern 32 may be deformed.

The processing pressure condition in the chamber 51 in the first gas exposure step (S03 in FIG. 1) is preferably set to about 133.3 to 1333.2 Pa (1.0 to 10.0 Torr), preferably 400.0 to 40. It is more preferable to set it to about 933.3 Pa (3.0 to 7.0 Torr). When the treatment pressure condition is less than 133.3 Pa (1 Torr), the inorganic compound contained in the first gas binds to the reactive functional group located on the outermost surface of the uneven pattern 32 and chemically forms on the outermost surface of the uneven pattern 32. There is a risk that a thin film of inorganic oxide (so-called ALD film) will be formed on the surface of the uneven pattern 32 due to the action of the oxidizing agent contained in the second gas, which will be described later.

The flow rate of the first gas supplied into the chamber 51 is not particularly limited, and is, for example, 8.45 × 10 ^-4 to 5.07 × 10 ^-2 Pa · m ³ / sec (5.0 to). It is about 300.0 sccm).

Next, an inert gas such as nitrogen (N ₂ ) is supplied into the chamber 51, and the surplus first gas is purged (exhausted) (S04 in FIG. 1). By purging (exhausting) the first gas containing the inorganic compound that did not contribute to the reaction with the reactive functional group from the inside of the chamber 51, the effect of the second gas exposure step (S05 in FIG. 1) described later is good. Played. That is, the residual reactive active group contained in the inorganic compound moiety bonded to the reactive functional group inside the uneven pattern 32 can be efficiently hydrolyzed. The first gas purging step (S04 in FIG. 1) can be carried out, for example, for about 10 to 10,000 seconds.

Subsequently, the uneven pattern 32 is exposed to a second gas containing an oxidizing agent under predetermined conditions (second gas exposure step, S05 in FIG. 1). By exposing the concavo-convex pattern 32 exposed to the first gas to the second gas, the residual reactive active groups contained in the inorganic compound moiety bonded to the reactive functional group of the resin material constituting the concavo-convex pattern 32 are hydrolyzed. Is replaced with a hydroxyl group. Since the dehydration condensation reaction occurs after that, the etching resistance of the uneven pattern 32 can be improved. The "predetermined conditions" in the second gas exposure step (S05 in FIG. 1) include the dimensions of the uneven pattern 32, the type of the resin material constituting the uneven pattern 32, and the type of the oxidizing agent contained in the second gas. Conditions can be set as appropriate in consideration of various conditions such as the hard mask layer 20 for etching using the uneven pattern 33 with improved etching resistance as a mask and the type of material constituting the base material 10.

The oxidizing agent contained in the second gas may be any as long as it can replace the residual reactive active group contained in the site of the inorganic compound bonded to the reactive functional group with a hydroxyl group, for example, water (H ₂ ). O), oxygen (O ₂ ), ozone, hydrogen peroxide and the like can be mentioned.

When the inorganic compound contained in the first gas is trimethylaluminum and the reactive functional group is a carbonyl group, as shown in the following reaction formula (2), the residue contained in the dimethylaluminum moiety bonded to the carbonyl group. The reactive active group (two methyl groups) is hydrolyzed by water as an oxidizing agent and replaced with a hydroxyl group. Then, as shown in the following reaction formula (3), a dehydration condensation reaction of the dihydroxyaluminum moiety occurs.

The time for exposing the uneven pattern 32 to the second gas (second gas exposure time) is preferably 1 to 3600 seconds, more preferably 30 to 1000 seconds. If the second gas exposure time is less than 1 second, the hydrolysis reaction of the residual reaction active group contained in the inorganic compound site bonded to the reactive functional group inside the uneven pattern 32 may not be sufficiently performed.

In the second gas exposure step (S05 in FIG. 1), similarly to the first gas exposure step (S03 in FIG. 1), the temperature condition is equal to or lower than the melting point of the resin material constituting the uneven pattern 32, preferably lower than the glass transition temperature. Therefore, it is preferable to expose the uneven pattern 32 to the first gas. This makes it possible to promote the hydrolysis reaction of the residual reactive active group contained in the inorganic compound moiety bonded to the reactive functional group while preventing the uneven pattern 32 made of resin from being softened and deformed.

The processing pressure condition in the chamber 51 in the second gas exposure step (S05 in FIG. 1) is preferably set to about 133.3 to 1333.2 Pa (1.0 to 10.0 Torr), preferably 400.0 to 40. It is more preferable to set it to about 933.3 Pa (3.0 to 7.0 Torr).

Next, an inert gas such as nitrogen (N ₂ ) is supplied into the chamber 51, and the surplus second gas is purged (exhausted) (S06 in FIG. 1). The second gas purging step (S06 in FIG. 1) can be carried out, for example, for about 30 to 10000 seconds.

This series of gas exposure steps (S03 to S06 in FIG. 1) is set as one cycle, and preferably a plurality of cycles are repeated. More preferably, the gas exposure step (S03 to S06 in FIG. 1) is repeated for 3 to 5 cycles. By repeating the above gas exposure steps (S03 to S06 in FIG. 1) for a plurality of cycles, the inorganic compound can be efficiently chemically reacted inside the uneven pattern 32. As a result, the etching resistance can be effectively improved without changing the dimensions of the uneven pattern 32. On the other hand, if the number of repetitions of the gas exposure step (S03 to S06 in FIG. 1) becomes too large (for example, more than 5 cycles), an excess component (inorganic oxide) is deposited on the surface of the uneven pattern 32, and the unevenness is formed. There is a risk of increasing the dimensions of the pattern 32.

Subsequently, the hard mask layer 20 is etched using the uneven pattern 33 attached to the gas exposure step (S03 to S06 in FIG. 1) as a mask to form the hard mask pattern 21 (FIG. 3 (C)). reference). In the present embodiment, since the etching resistance of the uneven pattern 33 is improved, it is possible to prevent the uneven pattern 33 from disappearing during the etching process of the hard mask layer 20. Therefore, the hard mask pattern 21 having extremely high dimensional accuracy is formed.

Using the hard mask pattern 21 thus formed as a mask, the first surface 11 side of the base material 10 is etched to form the uneven structure 1a (see FIG. 3D), and finally the hard mask pattern. By removing 21 (see FIG. 3E), the concave-convex structure 1 is manufactured. Examples of the concavo-convex structure 1 manufactured in the present embodiment include a nanoimprint mold, a semiconductor chip having a wiring pattern as the concavo-convex structure 1a, and the like.

As described above, in the present embodiment, the uneven pattern 33 used as a mask for forming the hard mask pattern 21 by etching has extremely excellent etching resistance, so that the hard mask pattern 21 has high accuracy. Is formed by. Therefore, the uneven structure 1a formed by using the high-precision hard mask pattern 21 as an etching mask is also formed with high accuracy. Moreover, since the etching resistance of the uneven pattern 33 is improved, the film thickness of the hard mask layer 20 (hard mask pattern 21) can be increased. Therefore, the uneven structure 1a having a large aspect ratio can be formed on the first surface 11 side of the base material 10 with high accuracy. As described above, according to the present embodiment, it is possible to manufacture the concavo-convex structure 1 having the concavo-convex structure 1a with high accuracy.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

In the above embodiment, an embodiment in which the uneven pattern 32 is formed on the hard mask layer 20 in the base material 10 on which the hard mask layer 20 is formed on the first surface 11 has been described as an example (FIG. 2 (FIG. 2). A)-(D)), the present invention is not limited to such an embodiment. For example, the uneven pattern 32 may be formed on the first surface 11 of the base material 10 having no hard mask layer 20. In general, many of the resin materials constituting the uneven pattern 32 have a small difference from the etching rate of the material constituting the base material 10, and when the base material 10 is etched using the uneven pattern that does not improve the etching resistance as a mask. The problem that the uneven pattern disappears during the etching process of the base material 10 and the shoulder portion of the uneven pattern is etched and formed on the first surface 11 of the base material 10 even if the uneven pattern does not completely disappear. There is a problem that the dimensional accuracy of the uneven structure is lowered. However, since the uneven pattern 33 formed in the above embodiment has extremely excellent etching resistance, the uneven structure 1a having good dimensional accuracy can be formed on the first surface 11 side of the base material 10.

Hereinafter, the present invention will be described in more detail with reference to examples and the like, but the present invention is not limited to the following examples and the like.

[Example 1]
An electron beam resist (ZEP520A, manufactured by Zeon Corporation) having a carbonyl group as a reactive functional group was applied by spin coating on one surface (first surface) of a silicon wafer to form a resist film having a film thickness of 70 nm. The silicon wafer was set in the chamber of the ALD apparatus (manufactured by Ultratech, product name: Savannah S200), and the gas exposure step (FIG. 1, S03 to S06) was carried out.

In the gas exposure step, first, a first gas containing trimethylaluminum (TMA) was supplied into the chamber under the following conditions (FIGS. 1 and S03).
Carrier gas: Nitrogen (N ₂ )
Processing pressure condition: 466.6 Pa (3.5 Torr)
Processing time: 1200 seconds Gas flow rate: 3.38 × 10 ^-3 Pa ・ m ³ / sec (20 sccm)
Chamber temperature: 85 ° C

Next, nitrogen (N ₂ ) is supplied into the chamber for 30 seconds to purge the first gas remaining in the chamber (FIGS. 1, S04), and then the second gas (H ₂ O) is supplied under the following conditions. It was supplied into the chamber (FIGS. 1, S05).
Processing pressure condition: 933.2 Pa (7.0 Torr)
Processing time: 500 seconds Gas flow rate: 3.38 × 10 ^-3 Pa ・ m ³ / sec (20 sccm)
Chamber temperature: 85 ° C

Finally, nitrogen (N ₂ ) was supplied into the chamber for 30 seconds to purge the second gas remaining in the chamber (FIGS. 1, S06).

After performing a series of gas exposure steps for 3 cycles, the resist film thickness (before etching) on the first surface of the silicon wafer was measured using a step meter (manufactured by Bruker, product name: DistanceX3D).

The first surface side of the silicon wafer after the gas exposure step is subjected to dry etching treatment (etching time: 60 seconds) with chlorine-based gas (Cl ₂ + O ₂ ), and the resist on the first surface of the silicon wafer after the etching treatment is performed. The film thickness (after etching) was measured using a step meter (manufactured by Bruker, product name: DistanceX3D). The resist film thickness measurement result is shown in FIG.

[Example 2]
The resist film thickness (before and after etching) on the first surface of the silicon wafer was measured in the same manner as in Example 1 except that a series of gas exposure steps were carried out for 5 cycles. The resist film thickness measurement results are also shown in FIG.

[Example 3]
The resist film thickness (before and after etching) on the first surface of the silicon wafer was measured in the same manner as in Example 1 except that a series of gas exposure steps were carried out for 10 cycles. The resist film thickness measurement results are also shown in FIG.

[Comparative Example 1]
The resist film thickness (before and after etching) on the first surface of the silicon wafer was measured in the same manner as in Example 1 except that a series of gas exposure steps were carried out for one cycle. The resist film thickness measurement results are also shown in FIG.

[Example 4]
The resist film thickness (before and after etching) on the first surface of the silicon wafer was measured in the same manner as in Example 2 except that the processing time for supplying the first gas was 100 seconds. The resist film thickness measurement results are also shown in FIG.

[Example 5]
The resist film thickness (before and after etching) on the first surface of the silicon wafer was measured in the same manner as in Example 3 except that the processing time for supplying the first gas was 100 seconds. The resist film thickness measurement results are also shown in FIG.

[Comparative Example 2]
The resist film thickness (before and after etching) on the first surface of the silicon wafer was measured in the same manner as in Comparative Example 1 except that the processing time for supplying the first gas was 100 seconds. The resist film thickness measurement results are also shown in FIG.

[Comparative Example 3]
The resist film thickness (before and after etching) on the first surface of the silicon wafer was measured in the same manner as in Example 1 except that the processing time for supplying the first gas was 100 seconds. The resist film thickness measurement results are also shown in FIG.

In the dry etching treatment with chlorine-based gas (Cl ₂ + O ₂ ) in Examples 1 to 5 and Comparative Examples 1 to 3, a metal chromium film (thickness: 1 to 100 nm) as a hard mask layer is etched to obtain a hard mask pattern. It is a general treatment method and treatment condition to form. As shown in FIG. 5, in Examples 1 to 5, it can be seen that a sufficient amount of resist remains after the dry etching process. From this result, it can be said that the etching resistance of the resist pattern can be improved by performing the gas exposure step (FIGS. 1, S03 to S06) after setting appropriate conditions.

[Test Example 1]
The composition of the silicon wafer (Example 2) after a series of gas exposure steps in the depth direction from the first surface side is determined by the time-of-flight secondary ion mass spectrometer (TOF-SIMS device, manufactured by ionTOF), product name: Analysis was performed using TOF-SIMS5). The results are shown in FIG.

As shown in FIG. 6, it was confirmed that the resist film formed on the first surface of the silicon wafer contained aluminum oxide. From this, it was confirmed that the TMA chemically reacted inside the resist film by the first gas exposure step.

From this result, the uneven pattern 32 composed of the resin material having the reactive functional group is exposed to the first gas containing the inorganic compound, the inorganic compound is chemically reacted inside the uneven pattern 32, and then the oxidizing agent is contained. It is presumed that the etching resistance of the uneven pattern 32 can be improved by exposing the uneven pattern 32 to the second gas.

[Example 6]
An ultraviolet curable resin composition having an acryloyl group as a reactive functional group and having the following composition was applied by inkjet on the hard mask layer 20 on the first surface 11 side of the quartz glass substrate 10 (152 mm × 152 mm). An imprint mold 40 having an uneven pattern 41 (line and space shape, dimension: 60 nm) is prepared, and the uneven pattern 41 is applied to the uneven pattern 41 on the hard mask layer 20 by using the imprint mold 40 as droplets of an ultraviolet curable resin composition. The ultraviolet curable resin composition was developed on the hard mask layer 20 to form an imprint resin film 30. In that state, the imprint resin film 30 was cured by irradiating with ultraviolet rays, and the imprint mold 40 was separated to form a resin uneven pattern 31 on the hard mask layer 20.

<UV curable resin composition>
-Isobornyl acrylate 38% by mass
-Ethylene glycol diacrylate 20% by mass
-Butyl acrylate 38% by mass
-2-Hydroxy-2-methyl-1-phenyl-propane-1-one 2% by mass
-2-Perfluorodecylethyl acrylate 1% by mass
・ Methylperfluorooctanoate 1% by mass

After removing the residual film portion 31c of the resin uneven pattern 31 by oxygen plasma ashing treatment, the quartz glass substrate 10 is set in the chamber of the ALD device (manufactured by Ultratech Co., Ltd., product name: Savannah S200) and the gas exposure step (FIG. 1, S03 to S06) were carried out.

In the gas exposure step, first, a first gas containing trimethylaluminum (TMA) was supplied into the chamber under the following conditions (FIGS. 1 and S03).
Carrier gas: Nitrogen (N ₂ )
Processing pressure condition: 466.6 Pa (3.5 Torr)
Processing time: 1200 seconds Gas flow rate: 3.38 × 10 ^-3 Pa ・ m ³ / sec (20 sccm)
Chamber temperature: 85 ° C

Next, nitrogen (N ₂ ) is supplied into the chamber for 30 seconds to purge the first gas remaining in the chamber (FIGS. 1, S04), and then the second gas (H ₂ O) is supplied under the following conditions. It was supplied into the chamber (FIGS. 1, S05).
Processing pressure condition: 933.2 Pa (7.0 Torr)
Processing time: 500 seconds Gas flow rate: 3.38 × 10 ^-3 Pa ・ m ³ / sec (20 sccm)
Chamber temperature: 85 ° C

Finally, nitrogen (N ₂ ) was supplied into the chamber for 30 seconds to purge the second gas remaining in the chamber (FIGS. 1, S06). After performing a series of gas exposure steps for 5 cycles, the uneven pattern 32 was observed using an electron microscope (LWM9000, manufactured by Leica). The SEM image of the unevenness pattern 32 is shown in FIG.

[Comparative Example 4]
The unevenness pattern after the gas exposure step was observed in the same manner as in Example 1 except that the synthetic quartz substrate was subjected to the gas exposure step without removing the residual film portion 31c of the resin uneven pattern 31. An SEM image of the uneven pattern is shown in FIG.

As shown in FIGS. 7 and 8, the uneven pattern 32 of Example 6 is not deformed, but in the uneven pattern of Comparative Example 4, the uneven pattern made of the ultraviolet curable resin is partially softened. It was confirmed that it was deformed in this way. From these results, it was clarified that the deformation of the uneven pattern 32 can be prevented by removing the residual film portion 31c before carrying out the gas exposure step.

[Test Example 2]
Since the uneven pattern of Comparative Example 4 was deformed so as to soften, it is as follows to confirm whether or not the heating in the gas exposure step (FIGS. 1, S03 to S06) is the cause of the deformation of the uneven pattern. And a heat resistance test was conducted.

A resin concavo-convex pattern 31 before removing the residual film portion 31c was prepared in the same manner as in Example 6, and the resin concavo-convex pattern 31 was heat-treated (baked) at 90 ° C. for 1 hour. Then, the resin uneven pattern 31 before and after the heat treatment was observed using an electron microscope (SU-8000, manufactured by Hitachi, Ltd.). FIG. 9 shows an SEM image of the resin uneven pattern 31 before the heat treatment, and FIG. 10 shows an SEM image of the resin uneven pattern 31 after the heat treatment.

As is clear from the SEM images shown in FIGS. 9 and 10, it was confirmed that the resin uneven pattern 31 is not deformed even if the resin uneven pattern 31 is heat-treated. From this result, the inorganic compound contained in the first gas chemically reacts with the ultraviolet curable resin constituting the unevenness pattern 31 inside the resin unevenness pattern 31 by a series of gas exposure steps (FIGS. 1, S03 to S06). As a result, the resin uneven pattern 31 is distorted, and it is considered that a large distortion is particularly caused because the resin uneven pattern 31 (convex portion 31a) is connected via the residual film portion 31c. As a result, it is presumed that the resin uneven pattern 31 (convex portion 31a) is deformed. On the other hand, as in Example 6, by performing the gas exposure step (FIGS. 1, S03 to S06) after removing the residual film portion 31c of the resin concavo-convex pattern 31, each convex portion of the concavo-convex pattern 32 is made of quartz glass. It will be independent on the substrate 10. Therefore, it is considered that the deformation of the uneven pattern 32 due to the distortion is suppressed.

Therefore, as in Example 6, by removing the residual film portion 31c before performing the gas exposure step, the unevenness pattern 32 can be prevented from being deformed, and the unevenness pattern 32 having improved etching resistance can be obtained. It was confirmed that it can be formed.

INDUSTRIAL APPLICABILITY The present invention is useful as a method for forming a resin uneven pattern used as an etching mask in a replica mold, a semiconductor device manufacturing process, or the like by an imprint method.

1 ... Concavo-convex structure 10 ... Base material 11 ... First surface 12 ... Second surface 20 ... Hard mask layer 21 ... Hard mask pattern 31 ... Resin concavo-convex pattern (resin pattern)
31a ... Convex portion 31b ... Concave portion 31c ... Remaining film portion 32 ... Concavo-convex pattern 40 ... Imprint mold 41 ... Concavo-convex pattern

Claims (11)

A base material having a first surface and a second surface facing the first surface and an imprint mold having a pattern forming surface formed by forming a plurality of concave patterns are prepared, and the first surface of the base material and the imprint mold are prepared. An active energy ray-curable resin is interposed between the pattern-forming surface and the imprint process, and a plurality of convex portions, a plurality of concave portions, and a residual film located at the bottom of the concave portions corresponding to the plurality of concave patterns are performed. A pattern forming step of forming a resin pattern having a portion on the first surface of the base material,
A step of removing the residual film portion of the resin pattern and a step of removing the residual film portion.
By exposing the resin pattern from which the residual film portion has been removed to a first gas containing an inorganic compound exhibiting Lewis acidity under predetermined conditions, the inorganic compound and the active energy ray-curable resin constituting the resin pattern are formed. In the first gas exposure step of chemically reacting with and inside the resin pattern,
After the first gas exposure step, it has a second gas exposure step of exposing the resin pattern to a second gas containing an oxidizing agent.
A pattern forming method, characterized in that each of the first gas exposure step and the second gas exposure step is performed for 1 second or longer . A base material having a first surface and a second surface facing the first surface and an imprint mold having a pattern forming surface formed by forming a plurality of concave patterns are prepared, and the first surface of the base material and the imprint mold are prepared. An active energy ray-curable resin is interposed between the pattern-forming surface and the imprint process, and a plurality of convex portions, a plurality of concave portions, and a residual film located at the bottom of the concave portions corresponding to the plurality of concave patterns are performed. A pattern forming step of forming a resin pattern having a portion on the first surface of the base material,
A step of removing the residual film portion of the resin pattern and a step of removing the residual film portion.
By exposing the resin pattern from which the residual film portion has been removed to a first gas containing an inorganic compound exhibiting Lewis acidity under predetermined conditions, the inorganic compound and the active energy ray-curable resin constituting the resin pattern are formed. In the first gas exposure step of chemically reacting with and inside the resin pattern,
After the first gas exposure step, the second gas exposure step of exposing the resin pattern to the second gas containing an oxidizing agent
Have,
In the first gas exposure step, the resin material constituting the resin pattern is heated under a temperature condition lower than the glass transition temperature, and the resin pattern from which the residual film portion is removed is exposed to the first gas.
A pattern forming method, characterized in that, in the second gas exposure step, the resin material constituting the resin pattern is heated under a temperature condition lower than the glass transition temperature, and the resin pattern is exposed to the second gas. The pattern forming method according to claim 1 or 2 , wherein the gas exposure step including the first gas exposure step and the second gas exposure step is repeated a plurality of times. 3. The third aspect of the present invention is characterized in that the time for exposing the resin pattern to the first gas in the first gas exposure step is longer than the time for exposing the resin pattern to the second gas in the second gas exposure step. The pattern forming method described. The time for exposing the resin pattern to the first gas in the first gas exposure step is shorter than the time for exposing the resin pattern to the second gas in the second gas exposure step.
The pattern forming method according to claim 3 , wherein the gas exposure step is repeated 5 times or more. The pattern forming method according to any one of claims 1 to 5 , wherein the thickness of the residual film portion is 1 to 20 nm. The pattern forming method according to any one of claims 1 to 6 , wherein the size of the resin pattern is 5 nm or more and less than 30 nm at a half pitch. The pattern forming method according to any one of claims 1 to 7 , wherein the resin pattern has an aspect ratio of 0.5 to 2.5. The pattern forming method according to any one of claims 1 to 8 , wherein the substrate is a quartz glass substrate or a silicon substrate. A pattern is formed on the first surface of the base material by the pattern forming method according to any one of claims 1 to 9 .
A method for manufacturing an uneven structure, which comprises etching the first surface side of the base material using the pattern as a mask. A pattern is formed on the hard mask layer in the base material having the hard mask layer formed on the first surface by the pattern forming method according to any one of claims 1 to 9 .
By etching the hard mask layer using the pattern as a mask, a hard mask pattern is formed.
A method for manufacturing an uneven structure, which comprises etching the first surface side of the base material using the hard mask pattern as a mask.

Images